Hi Guys...fitted a re-built crank to my BSA Bantam 175 2 stroke a few days ago...the bearing are caged needle rollers.
Second outing I could hear a metal to metal scrapping sound...fearing the worse I stripped the engine again.
Nothing obvious....
On first assembly I noticed that the little end bearing was a very snug fit once the conrod pin and bearing where assembled....no play what so ever...also turning the piston on after assembly I could feel a slight notchy feel.
When I looked at it after stripping..it looked as thought the piston pin was getting hot where the bearing runs...also it would not pust out of the piston easy...needed light drifting out...on first assemble it was a light push fit into the piston and bearing.
SO...could a tight little end bearing cause a screeching sound that somebody in a following car could hear...if say it seized on the pin after getting hot.
The engine has only done around 20 miles since its re-build.
All the other bearing in the engine have done less than 1000mls of light road use...they all feel free and smooth.
The big end still looks ok nothing obvious.
Ideas please guys.
Recently bought my 1st ever motorcycle...a humble BSA Bantam B175...I am enjoying using my Bantam so much...doe all I need. My car that I use daily is an old series Landrover that I bought new 40 years ago and has just become tax free.
well its not supposed to be tight in the little end but it is supposed to be tight in the piston . piston warmed in boiling water and pin should go in easy if its tightening in the little end the there's a problem .
#702229 - 07/19/177:10 pmRe: Squeal after fitting new crank roller bearings.
[Re: ducati2242]
Joined: Jun 2015 Posts: 16Nickjaxe
BritBike Forum member
So as the piston warm in use...the pin wont lock in the piston? it will actually be the opposite is that correct.
The supplier is looking into it for me now.
Fingers crossed.
Recently bought my 1st ever motorcycle...a humble BSA Bantam B175...I am enjoying using my Bantam so much...doe all I need. My car that I use daily is an old series Landrover that I bought new 40 years ago and has just become tax free.
#702596 - 07/24/1712:48 amRe: Squeal after fitting new crank roller bearings.
[Re: Nickjaxe]
Often the pin turns in the piston on these old brits, not supposed to... but on rare occasions they do. However they should be turning within the bearing. If the pin was a sliding fit in the needle roller when fitted it should Still be now.. was it assembled dry? Or with engine oil?
Which ever way it looks like you need a new little end bearing. Make a puller using a bolt through both bearings, a socket covering the end where the old bearing is being pulled to (big enough to house the bearing ), and a washer which comfortably is bigger than the cage of the bearing. Wind the bolt Up pulling one bearing inside the other.
I forget bearing terms, but ensure that it is a close coupled needle roller (roller directly next to roller) there are some bearings which have about 10 rollers and are Seperated by a plastic cage. These are sold as little end bearings but they are the wrong application for this bearing type.
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